Stokhos_GrowthRules.hpp

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#ifndef STOKHOS_GROWTH_RULES
#define STOKHOS_GROWTH_RULES
 
namespace Stokhos {
 
  template <typename value_type>
  class GrowthRule {
  public:
 
    GrowthRule() {}
 
    virtual ~GrowthRule() {}
 
    virtual value_type operator() (const value_type& x) const = 0;
  };
  
  template <typename value_type>
  class IdentityGrowthRule : public GrowthRule<value_type> {
  public:
    IdentityGrowthRule() {}
 
    virtual ~IdentityGrowthRule() {}
 
    virtual value_type operator() (const value_type& x) const { return x; }
  };
 
  template <typename value_type>
  class LinearGrowthRule : public GrowthRule<value_type> {
  public:
    LinearGrowthRule(const value_type& a_ = value_type(1), 
         const value_type& b_ = value_type(0)) : 
      a(a_), b(b_) {}
 
    virtual ~LinearGrowthRule() {}
 
    virtual value_type operator() (const value_type& x) const { return a*x+b; }
 
  protected:
 
    value_type a;
 
    value_type b;
  };
 
 
  template <typename value_type>
  class EvenGrowthRule : public GrowthRule<value_type> {
  public:
    EvenGrowthRule() {}
 
    virtual ~EvenGrowthRule() {}
 
    virtual value_type operator() (const value_type& x) const { 
      if (x % value_type(2) == value_type(1)) return x+value_type(1);
      return x;
    }
 
  };
 
  template <typename value_type>
  class ClenshawCurtisExponentialGrowthRule : public GrowthRule<value_type> {
  public:
    ClenshawCurtisExponentialGrowthRule() {}
 
    virtual ~ClenshawCurtisExponentialGrowthRule() {}
 
    virtual value_type operator() (const value_type& x) const { 
      if (x == value_type(0)) return value_type(0);
      return std::pow(value_type(2),x-value_type(1));
    }
 
  };
 
  template <typename value_type>
  class GaussPattersonExponentialGrowthRule : public GrowthRule<value_type> {
  public:
    GaussPattersonExponentialGrowthRule() {}
 
    virtual ~GaussPattersonExponentialGrowthRule() {}
 
    virtual value_type operator() (const value_type& x) const { 
      // Gauss-Patterson rules have precision 3*2*l-1, which is odd.
      // Since discrete orthogonality requires integrating polynomials of
      // order 2*p, setting p = 3*2*{l-1}-1 will yield the largest p such that
      // 2*p <= 3*2^l-1
      if (x == value_type(0)) return value_type(0);
      return 3*std::pow(value_type(2),x-value_type(1))-value_type(1);
    }
 
  };
 
}
 
#endif